1. Technical Field
The present disclosure relates generally to surgical instruments, and more specifically to quick connect interfaces used to connect a shaft of a replaceable tool to a drive mechanism.
2. Background Information
Quick connect interfaces (or simply “quick connects”) are widely used in surgical instruments to connect a shaft of a replaceable tool, such as a bit, to a drive mechanism, such as a ratcheting or non-ratcheting handle or a motor-operated drive. These surgical instruments may be used to perform a variety of surgical tasks, including drilling, reaming, tapping, placement of bone screws, assembly of spinal constructs, and the like. One common type of quick connect interface that may be employed is an Association for Osteosynthesis (AO)-style quick connect interface, typically referred to simply as an “AO quick connect interface”. Such an interface may be used with a wide variety of different types of replaceable tools, as well as different drive mechanisms.
A typical AO quick connect interface is configured to receive an end of a shaft having a D-shaped profile. A flat portion defined by the D-shaped profile of engages another flat portion (referred to herein as the “AO flat”) formed in an inner cavity of the AO quick connect interface. This engagement prevents rotation of the shaft with respect to the interface. The shaft may be retained in the interface by the operation of ball bearings. Two ball bearings are generally positioned radially about a central axis of the interface, about 180 degrees apart. The ball bearings may engage a groove formed in the end of the shaft. The ball bearings are often held by a substantially straight walled portion of the sleeve.
While such an arrangement may prevent removal of a replaceable tool, it may not hold the tool very securely. There is often substantial axial and lateral play. There may be minor variations in the shaft of replaceable tools, such that diameters of the groove may vary from one replaceable tool to the next. However, ball bearings positioned radially about 180 degrees apart, and held by straight walled portions, cannot effectively adapt to such variation. This may results in each replaceable tool fitting differently. In some cases, the fit may result in excessive amounts of play, such that the surgical instrument has a generally “sloppy” feel. This feel may be unsettling to a surgeon trying to perform a delicate surgical procedure.
Further, such an arrangement may be costly to manufacture to precise tolerances. To maintain the body of the interface as a single component, and avoid openings that would compromise function, one typically must access the region where the AO flat is to be formed through the inner cavity. With many designs, this requires the use of wire-electrical discharge-machining (wire-EDM) in the manufacturing process. While wire-EDM is capable of this type of work to very precise tolerances, it is generally a costly process, and therefore may not be suitable for low-cost instruments. Previous attempts to avoid the use of wire-EDM have generally involved multi-piece bodies that have introduced other issues, for example, have introduced unwanted play.
Accordingly, there is a need for an improved quick connect interface.